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  • 1
    Electronic Resource
    Electronic Resource
    3-Ethyl-2,5-dimethylpyrazine, a component of the trail pheromone of the antMessor bouvieri (1989)
    Springer
    Cellular and molecular life sciences 45 (1989), S. 487-489 
    Details
    ISSN: 1420-9071
    Keywords: Messor bouvieri ; Formicidae ; 3-ethyl-2,5-dimethylpyrazine ; trail pheromone ; poison gland ; anabasine ; Dufour gland ; Tapinoma simrothi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 3-Ethyl-2,5-dimethylpyrazine, found in the poison gland of workers, induces trail following in the Mediterranean harvester antMessor bouvieri. The poison gland contains on average 9 ng of this trail pheromone component. The alkaloids anabasine and anabaseine are also present in this gland, but induce no reaction in workers. Trail following is also induced by substances present in the Dufour gland, but the combined effect of both glands shows no synergism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01952041
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  • 2
    Electronic Resource
    Electronic Resource
    Timing of hatching inAmmodytes marinus from Shetland waters and its significance to early growth and survivorship (1996)
    Springer
    Marine biology 126 (1996), S. 143-152 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The significance of hatch date for the growth and survival of the sandeel,Ammodytes marinus, was investigated using otolith microstructure. Hatch dates of 2 to 6 mo-old juvenileA. marinus caught near Shetland were compared between 1990 and 1992, during which period year-class strength varied by more than an order of magnitude. The hatch-date distribution of juveniles in the 1992 year-class was compared with that estimated directly from the abundance of newly emerged larvae on the spawning grounds. The extent of larval hatching periods in 1990 and 1991 was also estimated from continuous plankton-recorder data. There were significant differences in hatching periods between all three years, hatching in 1990 and 1992 being markedly earlier than the long-term mean peak in hatching indicated from archival data. Most individuals from the 1991 year-class attained a larger size by July than those in other year-classes, despite hatching later. Variation in individual growth rates both within and between year-classes indicated that there was a seasonal cycle of growth opportunity in all years investigated. The study suggests that the degree of coupling between hatching and the onset of spring secondary production may be an important contributory factor to year-class variability in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571386
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  • 3
    Electronic Resource
    Electronic Resource
    Structure of hexagonal and cubic CdS heteroepitaxial layers on GaAs studied by transmission electron microscopy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2081-2083 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial heteroepitaxial growth and structure of thin CdS layers on GaAs has been studied by conventional and high-resolution transmission electron microscopy. The work highlights the dependence of CdS crystal type on GaAs substrate orientation. Wurtzite-structure CdS is formed on (111)A GaAs and it is found to relieve misfit stresses by the introduction of interfacial defects, often associated with steps at the interface. Sphalerite-structure CdS is produced by initial growth on (001)GaAs and, in this case, misfit stresses are more slowly relieved, first with the formation of an asymmetrical array of interfacial dislocations and inclined stacking faults.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102114
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  • 4
    Electronic Resource
    Electronic Resource
    Calcium binding by soluble matrix of the otoliths of Atlantic salmon, Salmo salar L. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 38 (1991), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1991.tb03149.x
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  • 5
    Electronic Resource
    Electronic Resource
    Ovarian development, spawning frequency and batch fecundity in Encrasicholina heteroloba (Ruppell, 1858) (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 40 (1992), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A histological and gravimetric analysis of oocyte development in Encrasicholina heteroloba (Ruppell, 1858) indicated that this species spawns serially and has a group-synchronous mode of ovarian development. A six stage maturity scale, based on both external morphology and oocyte composition, was proposed to classify ovarian development in E. heteroloba. The incidence of females with hydrated oocytes and post-ovulatory follicles in samples from two regions; the south Java Sea and Roviana lagoon, in the Solomon Islands were used to estimate spawning frequency. Estimates of mean inter-spawning intervals ranged from around 2 days in fish from Roviana lagoon to up to 16.7 days in fish from the south Java Sea. Batch fecundity was determined from the number of oocytes in the largest oocyte size class in ripe stage ovaries. Batch fecundity was related to size and was significantly greater for a given size in the Roviana lagoon population (F= 0.081 ×L4.89, Roviana population; F= 1.682 ×L2.83, Jepara population).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1992.tb02630.x
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  • 6
    Electronic Resource
    Electronic Resource
    Otolith and somatic growth rates in Atlantic salmon parr, Salmo salar L: evidence against coupling (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 36 (1990), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: It is often assumed that otolith growth is in some way dependent on somatic growth (i.e. that the two processes are coupled). We examined the relationships between sagitta radius and fork length in 0+ Atlantic salmon parr that would subsequently smolt aged 1 + (UMG fish) or 2+ (LMG fish). Repeated measurements of fork lengths of individually marked parr, taken over a 211-day period from first feeding, were compared to sagitta radii on the same measuring dates (obtained by analysis of daily increments). The results showed that there was a linear relationship between fork length and otolith radius in UMG parr. However, this was not true for LMG parr. These fish enter a state of natural anorexia in their first autumn (despite excess food), but their otoliths continued to grow at the same rate despite the virtual cessation of somatic growth; they had therefore developed disproportionately large otoliths by the end of the study period. The relative growth rates of soma and otoliths first changed in LMG fish in late July/early August; this is the most precise estimate yet obtained of the timing of divergence in the developmental pathways of UMG and LMG parr. The rate of sagitta accretion was consistently lower in LMG parr, possibly indicating a lower metabolic rate in these fish. The results are discussed in relation to previous theories of the relationship between otolith and somatic growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1990.tb05599.x
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  • 7
    Electronic Resource
    Electronic Resource
    CdS/CdSe intrinsic Stark superlattices (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 907-915 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained layer superlattices of wurtzite CdS/CdSe have been grown on (111)A GaAs substrates by metalorganic chemical vapor deposition and their optical properties studied by photoluminescence spectroscopy. It is shown that the superlattice layers contain giant strain-induced piezoelectric fields exceeding 2×108 V m−1. These fields are similar to those reported for (111) orientated III–V superlattices, but an order of magnitude greater. The recombination energies from a series of samples provide evidence for a type II conduction band offset of 0.23±0.10 eV (the electron wells being in the CdS), with the band structure heavily modified by the internal electric fields. In addition, the photoluminescence peak emission energy shows a strong dependence on the excitation power. This is interpreted as further evidence for the effect of internal fields. We conclude that this system shows new effects not previously observed in II–VI compound superlattices. The large band-gap tunability and the space-charge effects offer possibilities for all-optical switching devices in the 700–1300-nm region of the spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351312
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  • 8
    Electronic Resource
    Electronic Resource
    The calibration of the strength of the localized vibrational modes of silicon impurities in epitaxial GaAs revealed by infrared absorption and Raman scattering (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 2589-2596 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: n-type silicon-doped epitaxial layers of gallium arsenide grown by molecular-beam epitaxy (MBE) or metal-organo chemical vapor deposition (MOCVD) have been investigated by measurements of the Hall effect and the strengths of the localized vibrational modes (LVM) of silicon impurities using both Fourier transform absorption spectroscopy and Raman scattering at an excitation energy of 3 eV close to the E1 band gap. Lines from Si(Ga) donors, Si(As) acceptors, Si(Ga)-Si(As) pairs, and Si-X, a complex of silicon with a native defect, were detected and correlated for the two techniques. The maximum carrier concentration [n] found for samples grown under standard conditions was 5.5×1018 cm−3. At higher doping levels Si-X becomes dominant and acts as an acceptor, so reducing [n]. An integrated absorption of 1 cm−2 in the Si(Ga) LVM line corresponds to 5.0±4×1016 atoms cm−3: a similar calibration applies to the Si(As) line, but for Si-X, an absorption of 1 cm−2 corresponds to only 2.7±1.0×1016 defects cm−3. Possible structures for Si-X are discussed but a definitive model cannot yet be proposed. MBE samples grown at 400 °C had values of [n] close to 1019 cm−3, and a negligible concentration of Si-X. On annealing, [n] decreased and Si-X defects were produced together with site switching of Si(Ga) to Si(As). These results are important to the understanding of the mechanism of silicon diffusion at low temperatures. The infrared absorption and Raman measurements are complementary. Absorption measurements made at a resolution of 0.1 cm−1 require layers greater than or equal to 1 μm in thickness doped to a level of 3×1017 cm−3 but require the prior elimination of free-carrier absorption. Raman measurements can be made on as-grown layers only 10 nm in thickness doped to a level of 2×1018 cm−3, but with a spectral resolution of only 5 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344224
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  • 9
    Electronic Resource
    Electronic Resource
    Cathodoluminescence imaging and spectroscopy of dislocations in Si and Si1−xGex alloys (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1087-1089 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dislocations in float-zone Si which has been plastically deformed and deliberately copper contaminated, and misfit dislocations in a relaxed Si1−xGex alloy layer grown on a Si substrate by molecular beam epitaxy, have been investigated by monochromatic and panchromatic cathodoluminescence imaging and by cathodoluminescence spectroscopy. The measurements show that the D3 and D4 luminescence features originate on the slip lines in plastically deformed Si and at the misfit dislocations in the Si1−xGex alloy layer whereas the D1 and D2 bands are dominant between the slip lines and the misfit dislocations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107676
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  • 10
    Electronic Resource
    Electronic Resource
    Spatial distribution of the luminescence in GaN thin films (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 57-59 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spatial dependence of the luminescence intensities at the band edge (364 nm) and at the "yellow'' defect-band (centered at 560 nm) regions for epitaxial GaN films have been studied using cathodoluminescence microscopy at room temperature. The films were grown by metalorganic chemical vapor deposition on (0001) sapphire substrates and were not intentionally doped. Significant nonuniformities in the band-to-band and in the yellow band emissions were observed. Yellow luminescence in small crystallites appears to originate from extended defects inside the grains and at low-angle grain boundaries. The size of band-to-band emission sites correlates with low-angle grain sizes observed by transmission electron microscopy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116756
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